A flange joint using flanges (i.e., disk-shaped larger-diameter portions formed at pipe ends) has hitherto been known as a joint for a location where pipes for feeding a fluid are jointed in a fashion removable as required. Methods for fixing the flanges are mainly grouped into a method of fastening the flanges with bolts, for example, and a method of clamping the flanges with a clamp, for example.
A clamp used in the above-described situation is generally configured as illustrated in FIG. 7. More specifically, respective ends of two clamping members (4, 5), each having a semicircular shape, are rotatably connected to each other through a connection member 6. A fastening member 28 is rotatably disposed at the other end of the lower clamping member 5, and a groove 31 into which the fastening member 28 is fitted is provided at the other end of the upper clamping member 4. A rod portion 29 of the fastening member 28 is threaded, and a butterfly nut 30 is meshed with the threaded rod portion. When fixing the flanges by the above-described clamp, the flanges are fitted into a groove 2 that is formed in inner surfaces of the clamping members, and the fastening member 28 is inserted into the groove 31 of the upper clamping member 4. The butterfly nut 30 is then tightened. As a result, the flanges are fixedly clamped upon application of a force in the direction of the pipe axis to the flanges by the action between the groove 2 formed in the inner surfaces of the clamping members and outer surfaces of the flanges. The above-mentioned general type of clamp has been variously improved (see, e.g., Patent Documents 1 and 2).
Patent Document 1 discloses a pipe-jointing clamp comprising a clamp body including a plurality of substantially arc-shaped clamp pieces, respective ends of the clamp pieces being pivotally connected to each other at a portion except for at least one location in each clamp piece, and a first screw member and a second screw member meshed with each other to fasten the not-pivotally-connected ends of the clamp pieces of the clamp body together, wherein a groove into which tapered flanges formed in short pipe members are fitted is circumferentially formed in an inner peripheral surface of each clamp piece, the first screw member is rotatably attached to one of the not-pivotally-connected ends of the clamp pieces, and a hole engageable with a ratchet tool is formed in the second screw member that pushes the other of the not-pivotally-connected ends of the clamp pieces in the axial direction of the first screw member.
Patent Document 2 discloses a pipe clamping joint used, when ferrules of pipes at a seam therebetween are abutted against each other with a gasket fitted into annular grooves recessed in contact surfaces of the ferrules, for preventing leakage of powdery materials, liquids, or gas flowing through pipes to the outside by being tightly fitted over outer peripheries of the abutted portions of the ferrules, wherein lower ends of a pair of clamp hands divided into halves each having a substantially semicircular shape and each having a groove capable of covering the outer peripheries of the abutted portions of the ferrules are rotatably connected to each other through a connection metal fixture, free end portions of the pair of clamp hands are bent upward in a state capable of being kept parallel to each other, thereby forming a pair of fastening portions that has a substantially C-shape when viewed from above, a link plate is rotatably attached to opposite lateral sides of one of the paired fastening portion through pins, an operating lever including a cam portion formed in a proximal end portion thereof is rotatably attached to distal end portions of the pair of link plates through pins, and a cam receiving recess against which the cam portion formed in the proximal end portion of the operating lever is pressed is recessed in the other fastening portion.